hrvatski

Microhardness characterization of Al-W thin films

Binary alloys of aluminum and tungsten are interesting because of various possible engineering applications, e.g. as a corrosion resistant coating or as a difussion barrier layer at higher temperatures, etc. Thin films of Al-W alloys (Al82W18 to Al50W50), were prepared on the sapphire or alumina substrates by magnetron cosputtering technique. It is revealed by X-ray diffraction that films inside a composition range Al82W18 to Al62W38 are amorphous, while further addition of tungsten resulted in a small fraction of crystalline W phase within a dominant amorphous phase. Vickers microhardness measurements at room temperature were performed on the as-prepared and annealed Al-W thin films to characterize their mechanical behaviour and to correlate it with microstructural changes. Microhardness values on the films varied from about 8-10 GPa for completely amorphous films, up to 20 GPa for two-phase films. Main reason for this increase is probably a presence of a minor fraction of crystalline tungsten phase, beside dominant amorphous one. Experiments dealing with the effects of annealing conditions during heat-treatment upon microhardness and structural changes are in progress.

Al-W tanki filmovi; Magnetronska kodepozicija; Rentgenska difrakcija; Vickersova mikrotvrdoća; Toplinska obrada.

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